Md. Farhad Ismail^a,*, M.A.I. Rashid^b , M. Mahbub^b

Frontiers in Heat and Mass Transfer, Vol.3, No.3, pp. 1-8, 2012, DOI:10.5098/hmt.v3.3.3002

Abstract Carbon nanotube (CNT) has been proven to be an effective material for the thermal management of MEMS-based devices due to its superior thermal conductivity. At the same time, micro-channel heat-sinks are widely used in electronic products as a high performance heat transfer device because of its simple construction, easy fabrication process and effective heat removal capability. A numerical study has been carried out to investigate the thermal-fluid characteristics of the aligned and staggered MWCNT (multi walled CNT) based micro pin fins having 650 µm long with hydraulic diameter of ~130 µm. Average heat transfer coefficients have been obtained for effective… More >

Alexandre Vaudrey^a,*, Philippe Baucour^b, François Lanzetta^b, Raynal Glises^b

Frontiers in Heat and Mass Transfer, Vol.3, No.3, pp. 1-8, 2012, DOI:10.5098/hmt.v3.3.3001

Abstract Producing electrical work in consuming chemical energy, the fuel cell (FC) is forced by the 2^nd law to reject heat to its surrounding. However, as it occurs for any other type of engine, this thermal energy cannot be exchanged in an isothermal way in finite time or through finite areas. As it was already done for various types of systems, including chemical engines, the fuel cell is here studied within the finite time thermodynamics framework. An endoreversible fuel cell is then defined, internally reversible but producing entropy during heat exchanges with its ambiance. Considering usual H₂/O₂ and H₂/air chemical reactions… More >

D. Srinivasacharya^∗, G. Swamy Reddy

Frontiers in Heat and Mass Transfer, Vol.3, No.4, pp. 1-9, 2012, DOI:10.5098/hmt.v3.4.3008

Abstract The natural convection heat and mass transfer along a vertical plate embedded in non-Newtonian Power-law fluid saturated porous medium in the presence of first order chemical reaction and radiation is studied. The governing partial differential equations are transformed into ordinary differential equations using similarity transformations. The resulting equations are solved numerically using Shooting method. The effect of radiation parameters and chemical reaction parameter and power law index on non-dimensional velocity, temperature and concentration fields are discussed. The variation of different parameters on heat and mass transfer rates is presented in tabular form. More >

Melanie Patrick^a, Messiha Saad^a,*

Frontiers in Heat and Mass Transfer, Vol.3, No.4, pp. 1-8, 2012, DOI:10.5098/hmt.v3.4.3007

Abstract Thermal characterization is essential to the proper assignment of composites to specific applications. Specific heat, thermal diffusivity, and thermal conductivity are critical in the engineering design process and in the analysis of aerospace vehicles, space systems, power generation, transportation systems, and energy storage devices including fuel cells. This paper examines the thermal properties through the thickness of Carbon-Carbon and the impact of Graphitization is explored. Following ASTM standards, the Flash Method and Differential Scanning Calorimetry measured thermal diffusivity and specific heat respectively. These measurements and density data allowed for the computation of thermal conductivity. More >

Krishnendu Bhattacharyya^*

Frontiers in Heat and Mass Transfer, Vol.3, No.4, pp. 1-6, 2012, DOI:10.5098/hmt.v3.4.3006

Abstract A mathematical model is presented to analyse the steady boundary layer slip flow and mass transfer with nth order chemical reaction past a porous plate embedded in a Darcy porous medium. Velocity as well as mass slips are considered at the boundary. The governing PDEs are transformed into self-similar nonlinear ODEs by similarity transformations. The reduced nonlinear equations are solved numerically. The momentum boundary layer thickness is reduced for increase of permeability and suction parameters, whereas it increases with blowing parameter. The increase of velocity slip parameter reduces the momentum boundary layer thickness and also enhances the mass transfer from… More >

F. Sharifi^a , H. Ghaedamini^b,*, M.R. Salimpour^a

Frontiers in Heat and Mass Transfer, Vol.3, No.4, pp. 1-10, 2012, DOI:10.5098/hmt.v3.4.3005

Abstract In the present study, conductive cooling of a disc is done by means of incomplete constant and variable cross-section highly conductive inserts embedded in radial and tributary configurations. Variational calculus is invoked to determine the optimum shape of the cross-sections of the inserts. Firstly, it is tried to derive an equation for thermal resistance of the disc for radial configuration of inserts based on the procedure used in constructal studies. This is done by implementing the optimized thermal resistances of elemental sectors. Then, the computed elemental sectors are put together so that they make branching configuration of inserts in the… More >

Mohammad Izadifar^a,b,*, Xiongbiao Chen^a,b

Frontiers in Heat and Mass Transfer, Vol.3, No.4, pp. 1-7, 2012, DOI:10.5098/hmt.v3.4.3004

Abstract Heat can be potentially used for accelerating biodegradation of implanted tissue engineered scaffolds. Cyclic and continuous radio frequency (RF) heating was applied to implanted chitosan and alginate scaffolds at 4 applied voltages, 3 frequencies, and 2 thermally conditioning environments. A 3D finite element model was developed to simulate the RF treatment. A uniform RF heating was achieved at the scaffold top. For alginate, voltage was the only significant RF heating factor while both frequency and voltage significantly affected RF heating of chitosan. Less temperature gradient across the scaffold was achieved at a conditioning environment at <30°C. Surrounding tissue was insignificantly… More >

A. Rasekh^a,*, D.D. Ganji^b, S. Tavakoli^b

Frontiers in Heat and Mass Transfer, Vol.3, No.4, pp. 1-6, 2012, DOI:10.5098/hmt.v3.4.3003

Abstract The present paper deals with the analysis of boundary layer flow and heat transfer of a nanofluid over a stretching circular cylinder in the presence of non-uniform heat source/sink. The governing system of partial differential equations is converted to ordinary differential equations by using similarity transformations, which are then solved numerically using the Runge–Kutta–Fehlberg method with shooting technique. The solutions for the temperature and nanoparticle concentration distributions depend on six parameters, Prandtl number Pr, Lewis number Le, the Brownian motion parameter Nb, the thermophoresis parameter Nt, and non-uniform heat generation/absorption parameters A*, B*. Numerical results are presented both in tabular… More >

Soumei Baba^a,*, Nobuo Ohtani^a, Osamu Kawanami^b, Koichi Inoue^c, Haruhiko Ohta^a

Frontiers in Heat and Mass Transfer, Vol.3, No.4, pp. 1-8, 2012, DOI:10.5098/hmt.v3.4.3002

Abstract Effects of tube orientation on flow boiling heat transfer coefficients were investigated for FC72 flowing in single mini-tubes with tube diameters of 0.13 and 0.51 mm to define boundaries on a dominant force regime map. For the tube diameter of 0.51 mm, when mass velocity and vapor quality was varied, heat transfer coefficients were influenced by tube orientation at Froude number Fr < 4, while the effect of tube orientation on heat transfer coefficients disappears at Fr > 4. The results indicated that the boundary between the body force dominated and the inertia dominated regimes was given by Fr ≈… More >

Mohamed S. El-Genk^a,b,c,∗, Amir F. Ali^a,c

Frontiers in Heat and Mass Transfer, Vol.3, No.4, pp. 1-14, 2012, DOI:10.5098/hmt.v3.4.3001

Abstract Advanced spreaders for cooling a 10 x 10 mm underlying computer chip with a central hot spot (CHS) could remove > 85 W of dissipated thermal power at junctions’ temperature < 100o C. The spreaders comprise a 1.6 - 3.2 mm thick Cu substrate and an 80-μm thick micro-porous copper (MPC) surface cooled by saturation nucleate boiling of PF-5060 dielectric liquid. Investigated are the effects of varying the heat flux at the chip’s 1 and 4 mm² CHS and the impedance of thermal interface material (TIM) between the Cu substrate and underlying chip. Results confirmed the effectiveness of the MPC… More >